[Small renal cell carcinomas and synchronous metastases]

Area of Science:

• Oncology
• Urology
• Pathology

Background:

• Renal cell carcinoma (RCC) incidence is rising, with more small tumors (≤4cm) detected incidentally.
• Guidelines recommend nephrectomy for small RCC, assuming favorable survival.
• The frequency of synchronous metastasis in small RCCs has not been well-established.

Purpose of the Study:

• To investigate the frequency of synchronous metastasis in patients diagnosed with small renal cell carcinoma (RCC) in Iceland.
• To compare characteristics and survival between small RCC patients with and without synchronous metastasis.

Main Methods:

• Retrospective study of 257 patients with RCC ≤4cm from 1102 RCC patients diagnosed in Iceland (1971-2010).
• Comparison of patients with metastasis versus localized disease.
• Review of hospital charts for histology, TNM-stage, and disease-specific survival.

Main Results:

• The proportion of small tumors increased significantly from 9% to 33% (2001-2010).
• 10% (25/257) of small RCC patients had synchronous metastases, primarily in lungs or bones.
• Patients with metastases were older, had larger tumors, higher nuclear grade and T-stage, and significantly worse 5-year survival (7% vs. 94%).

Conclusions:

• Synchronous metastasis is present in one out of ten small RCC patients at diagnosis.
• Small RCC should be considered a potentially systemic disease, even when detected incidentally.
• Findings challenge the assumption of universally favorable prognosis for small RCCs.